1. Field of the Invention
The present invention relates to a method and an apparatus for processing a leadframe on which electronic parts such as ICs are mounted and then molded in resin to seal them. The invention further relates to improvements in a method of processing a leadframe and an apparatus to which this method is applied, the processing referring to cutting of a predetermined portion of the leadframe, cutting of the leadframe to separate works (electronic parts each composing a product) on the leadframe, bending of a predetermined portion of the leadframe, or the like.
2. Description of the Background Art
A leadframe processing apparatus usually includes a leadframe loading unit for supplying, along a leadframe loading transport passage, a leadframe which has not undergone lead processing, a lead processing unit, and a leadframe unloading unit for discharging a leadframe which has undergone lead processing. The lead processing here refers to processes of cutting a leadframe, bending a leadframe, cutting (punching) a leadframe to separate works, i.e. components, therefrom, and the like.
The lead processing unit of the leadframe processing apparatus conventionally includes one press for processing (processing press). A plurality of sets of molds for processing (processing molds) are fixed to the press, the molds each having a punch and a die located at a pitch position corresponding to the pitch or spacing of the works or components on a leadframe. The press thus has a so-called progressive mold structure.
In the lead processing, a leadframe is intermittently supplied step by step to predetermined positions between punches and dies of the molds while cutting and bending processes or the like are performed by using the punches and dies.
A die set including a mold is attached to the conventional processing press. Therefore, if the processing press has a die set including a mold for cutting, it constitutes a lead cutting apparatus. If the processing press has a die set including a mold for bending, it constitutes a lead bending apparatus.
The conventional leadframe processing apparatus has a structure in which a plurality of sets of processing molds are fixed to one processing press. In order to adjust the pitch of the processing molds (punch and die of a die set) according to the pitch of the components or works on a leadframe such that the processing molds are surely attached to the processing press with high precision, a considerable proficiency is required. Such proficiency is also needed because such type of apparatus is an ultraprecision processing apparatus used for small-sized electronic parts.
Specifically, since each processing mold is fixed to one processing press, its processing function for a leadframe is inappropriate if alignment of the mold with the press is inaccurate, resulting in significant disadvantageous effects such as occurrence of defective parts or components.
One object of the present invention is to provide a method of processing a leadframe by which the pitch of processing presses (pitch of processing molds) as discussed above can readily and surely be adjusted with high precision according to the pitch of works on a leadframe when the leadframe is processed, and provide a processing apparatus to which this method is applied.
A method of processing a leadframe according to the invention which achieves the above object includes the steps of transporting a leadframe to load it to a lead processing unit having a plurality of sets of processing presses, adjusting the pitch of the plurality of processing presses according to the pitch of works or components on the leadframe, and performing a predetermined lead processing on the leadframe by the plurality of sets of processing presses after the step of adjusting the press pitch.
A leadframe processing apparatus according to the invention to implement the leadframe processing method of the invention above includes a leadframe loading unit placed along a loading transport passage of a leadframe for loading a leadframe which has not undergone lead processing, a lead processing unit coupled to the leadframe loading unit and having a plurality of sets of processing presses, a leadframe unloading unit coupled to the lead processing unit for unloading a leadframe which has undergone lead processing, and press pitch adjusting means for freely adjusting pitch of the plurality of sets of processing presses in the direction of the loading transport passage of a leadframe.
According to the method and apparatus for processing a leadframe of the present invention having the structure as described above, the pitch of a plurality of sets of processing presses provided to the lead processing unit is adjusted according to the pitch of works on a leadframe. Accordingly, with no proficiency in operation, the pitch of processing presses can easily and surely be adjusted with high precision according to the pitch of works on a leadframe. As a result, the operation of processing a leadframe can efficiently and surely be performed.
Preferably, in the leadframe processing apparatus of the invention, a fitting portion for a leadframe processing mold is placed at the processing press so as to directly attach the leadframe processing mold to the fitting portion. By such a structure, the leadframe processing mold can easily be attached to the processing press with high precision and the overall size of the leadframe processing apparatus can be decreased to accomplish superior practical effects such as reduction of cost and the like.
According to a preferred embodiment of the leadframe processing apparatus of the present invention, a sucking discharge mechanism for processing wastes is provided to the lead processing unit above and additionally control means is provided for automatically controlling the degree of sucking processing wastes by the sucking discharge mechanism. By this structure, the degree of sucking the processing wastes by the sucking discharge mechanism can automatically be controlled to achieve superior practical effects that the processing wastes in the lead processing unit can always be sucked and discharged appropriately.
According to another preferred embodiment of the leadframe processing apparatus of the invention, the lead processing unit includes a plurality of lead processing main bodies each having at least one processing press, and the plurality of lead processing main bodies are detachably coupled to each other. This structure thus achieves superior practical effects that the number of lead processing main bodies in the lead processing unit can easily and appropriately be adjusted depending on increase or decrease of the number of processing steps.
The means for adjusting the pitch of the presses in the leadframe processing apparatus of the present invention includes, for example, a screw shaft nonrotatably placed in the direction of leadframe loading transportation, a nut member which is engaged with the screw shaft and to which a processing press is coupled, and a driving motor which applies rotational force to the nut member via power transmission means. Using the press pitch adjusting means having the structure above, the pitch of processing presses can readily be adjusted by rotating the nut member with the rotational force applied by the driving motor to shift the nut member in the direction of the screw shaft, and thus simultaneously shifting the processing press coupled to the nut member.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.